1. Field of the Invention
This invention relates in general to well pumps, and in particular to a well pump enclosed by a capsule that selectively isolates the pump from annulus pressure within the well while permitting access to a portion of the well below the capsule.
2. Background of the Invention
Well pumps are utilized in low-pressure hydrocarbon wells for pumping the fluid to the surface. Submersible well pumps are mounted to an electrical motor, the pump and motor being submerged in the well. Typically, the pump has the discharge end connected to a string of tubing that extends to the surface of the well. Electrical power is supplied from the surface for operating the motor to drive the pump.
For certain remedial interventions, such as chemical/acid squeeze operations, the pump unit will be pulled along with the string of tubing. Test samplers and valves may be set below the pump unit to apply a high-test pressure to the well before the unit is pulled. This high pressure in the well annulus can damage the pump unit.
Previously, pump assemblies have been placed within shrouds or capsules for protection from sand or corrosion. These prior designs do not, however, disclose a selectively sealable capsule that permits access to a well below the level of the capsule. The prior art also does not disclose a method of protecting a submersible pump assembly from high pressure by enclosing it in a selectively sealable capsule.